Belle II/Superkekb: New Physics and the Next Generation Tom Browder, University of Hawai’I at Manoa

Belle II/SuperKEKB: New Physics and the Next Generation Tom Browder, University of Hawai’i at Manoa

Introduction, History and Motivation: What’s happening in high energy physics ?

Some Highlights from First Collisions and the Phase 2 Belle II Pilot Run.

The complex superconducting final focus is partially visible here (before closing the endcap). Physics and the Road Ahead to Phase 3, the first Physics run Vertex detector before Conclusion; opportunities installation for Vietnam The Geography of the International Belle II collaboration

Belle II now has grown to ~800 researchers from 26 countries

This is rather unique in Japan and Asia. The only comparable example is the T2K experiment at JPARC, which is also an international collaboration Including one very good one from Vietnam, Dong Van Thanh Youth and potential: There are ~267 graduate students in the collaboration What is happening these days in high energy physics ?

(Personal perspective, based on trips to international conferences and summer schools.)

Typical scenes in Hanoi, Vietnam NY Times on Aug 5, 2016

2016: US Some other media Belle II headlines on ICHEP: summer school, “Physicists look to @PNNL in the future as new Richland, particle dream dies” Washington “Particle Physics in Mourning”

“The End of the Beginning”

Friday August 5, 2016 at ICHEP in Chicago, the ATLAS and CMS collaborations announced that the 750 GeV di-photon excess had disappeared in the large Run II 13 TeV dataset. 2017 US Belle II School@Ole Miss New York Times, June 19, 2017

But since then, the silence from the energy frontier has been ominous. “The feeling in the field is at best one of confusion and at worst depression,” Adam Falkowski, a particle physicist at the Laboratoire de Physique Théorique d’Orsay in France, wrote recently in an article for the science journal Inference. “These are difficult times for the theorists,” Gian Giudice, the head of CERN’s theory department, said. “Our hopes seem to have been shattered. We have not found what we wanted.” Summer 2018

1200 international participants.

LHC High pt: Expected Standard Model (SM) t-tbar-Higgs coupling observed by CMS and ATLAS, SM Higgsb bbar evidence found, no SUSY (SUperSYmmetric) or extra particles.

Dark Matter: No dark matter (DM) signals in Xenon 1T or other leading DM experiments (i.e. DEAP(Canada), LUX (US), PandaX (China))

Neutrinos: Sterile neutrinos at reactors disfavored by Daya Bay results. Planck only needs 3 neutrinos for the CMB (Cosmic Microwave Background). Hints of a normal hierarchy for neutrino masses at NoVa at Fermilab. This is not what the theorists told us to expect ! US Belle II summer school July 2018, Cincinnati, Ohio

“Not found: Any evidence for additional particles. There's no sugar-coating this one: this was perhaps the greatest hope of most physicists. New particles at scales between 100 GeV and ~2 TeV were sorely hoped for, and at various times, some statistically suggestive evidence emerged for a few candidates. Unfortunately, with more and better data, this tentative evidence evaporated, and now, with Run I and Run II complete, there are not even any good suggestions of where such a new particle might be.

That means it's important to try new things, including general searches, says Gian Giudice, who heads CERN’s theory department and is not involved in any of the Remain Calm, Do not Panic ! experiments. “This is the right approach, at this point.” (Scientific American, Aug 2018) Stay calm. Don’t panic !! The intensity frontier will save you (again) as it has done many times in the past. (KLμμ, B + - + - mixing, AFB(e e μ μ ), Electroweak corrections etc…)

Beauty and the Beast

The legend is reborn Quantum Mechanical (QM) Finesse versus Brute Force

Energy conservation ?

Banking Analogy (may be easier to understand): At the Heisenberg Quantum Mechanical bank, customers with no collateral may take out billion Euro loans if they return the full loan within a billionth of a second.

If a beautiful but rare customer takes out such huge loans very frequently, the bank will take notice. Looks odd (or asymmetric) in the bank’s special full length mirror.

N.B. Sometimes it is much better to have a large collateral Werner Heisenberg, and pay back the loan directly after a longer time. Physicist and QM banker Time-dependent CP violation is “A Double-Slit experiment” with particles and antiparticles QM interference between two diagrams box diagram + tree diagram tree diagram Vtd b c J/ψ b t d d KS c + s s K c d d S d t b c J/ψ

Vtd

Measures the phase of the Vtd weak interaction coupling constant or equivalently the phase of Bd –anti Bd mixing. 10 0 Measurement of sin(2φ1)/sin(2β) in BCharmonium K modes

0 (cc)K B S B 0

J/ψKS J/ψKL J/ψKL

  1   1

sin2φ 1=0.667±0.023±0.012 sin2φ1=0.687±0.028±0.012 Af=0.006±0.016±0.012 Af=-0.024±0.020±0.016 PRL108,171802 (2012) PRD79,072009 (2009) Overpowering evidence for CP violation (matter-antimatter

asymmetries). >>>> The phase of Vtd is in good agreement with Standard Model expectations.11 This is the phase of Bd mixing. 2008: Critical Role of the B factories in Japan and the US in the verification of the Kobayashi- Maskawa hypothesis was recognized and cited by the Nobel Foundation

A single irreducible phase accounts for all the matter-antimatter asymmetries in particle physics.

CP violating effects in the B sector are O(1) rather than O(10-3) as in the kaon system. CP Violation is now included in most of the undergraduate particle physics textbooks.

I will skip the comic book or manga explanation of CP violation. I will also not cover the famous And I will gloss over competition/r the critical role of ace between the original Belle Belle and experiment in the BaBar to 2008 Nobel Prize for discover CP Kobayashi and violation in Maskawa. the b-sector in 2001.

Sorry this manga is all males. 2015: “Missing Energy Decays” of the B meson

New Frontier: Start of a NP program that will last a decade or more15. Standard Quantum Model 3-D Mechanical Billiard Table. Lepton Billiards

g Experimentally good for leptonic decays t = 1.0000 ± 0.0014 g to an accuracy much better than 1%. m G(K - ® m -n) To the 1% level, - - @ 1 G(K ® e n) But what about semi-leptonic decays of beauty ? τ

Now can access the e 3rd generation of leptons and couple to quarks ! Does that make a difference ? Unexpected competition from Belle LHCb@CERN Summer 2018 ICHEP: World Average is still ~4σ from the Standard Model

B(B ® D(*)tn) R(D(*) ) = B(B ® D(*)ln) The neutral BEH boson is now firmly established by experimental results from ATLAS and CMS. Now planning for future Higgs flavor factory facilities . (e.g ILC, HL-LHC, CEPC, FCC). N.B. SM has no charged Higgs PGU Question: What do these acronyms stand for ? Does the GP (Brout- Englert-Higgs particle) have a “brother” i.e. the charged Higgs ?

PGU Question: How would the LHC observe a charged Higgs ? Y. Nambu, 1921-2015 Measurements at Belle II and direct searches at hadron colliders take

complementary approaches. N.B. Leptoquarks are also possible. 20 Complementarity of e+ e- and LHC

The current combined Bτυ limit places a stronger constraint than direct searches from LHC exps. for the next few years.

1 ab-1

Belle II

Currently inclusive bsγ rules 2 out mH+ below ~480 GeV/c range at 95% CL (independent of This region is allowed tanβ), M. Misiak et al. (assuming no other NP)

http://arxiv.org/abs/1503.01789 21 Science Magazine Red Hot Flavor Physics

The stakes are getting higher

Science Magazine, April 20, 2017 Back to the SM More QM Leptonic Flavor Billiards billiard table (*) + - 2 BF(B ® K m m ) RK (*) (q ) = (*) + - BF(B ® K e e ) For experts: q2= M2(l+l-) Experts: Angular correlations in BK* l l also show deviations from the SM, 4-5σ

R is ~2.6σ from the SM K RK* ~2.1σ (low bin), 2.5σ (central bin) “Light DM” sensitivity in e+e-γ+nothing

This is hard. Requires a special new trigger that is being developed for Belle II. Should be tested during Phase III in 2019. 24 “Light DM” sensitivity in γ+nothing

25 The world is waiting January 2018 for our results.

https://www.nature.com/articles/d41586-018-00162-x SuperKEKB, the first new collider in particle physics since the LHC in 2008 (electron-positron (e+e-) rather than proton-proton (pp))

Some items to note: 1) Brand-new positron damping ring (commissioned spring 2018).

2) New 3 km positron ring vacuum chamber (commissioned in 2016). Optics and vacuum scrubbing this spring.

3) New complex superconducting final focus (commissioned this spring 2018). SuperKEKB/Belle II Luminosity Profile Belle/KEKB recorded ~1000 fb-1 . Now have to change units on y-axis to ab-1

Beam currents only a factor of two higher than KEKB (~PEPII)

“nano-beams” are the key; vertical beam size is 50nm at the IP

N.B. To realize this steep turn-on, requires close cooperation between Belle II and SuperKEKB [and some international collaboration on the accelerator, including the US and Europe].

Vietnam: The old 1 ab-1 Belle dataset can be analyzed by Belle II collaborators. Some Belle II jargon Phase 1: Simple background commissioning detector (diodes, diamonds TPCs, crystals…). No final focus. Only single beam background studies possible [started in Feb 2016 and completed in June 2016.

off

Phase 2: More elaborate inner background commissioning detector (VXD samples). Full Belle II outer detector. Full superconducting final focus. No vertex detectors. Collisions ! [Phase 2 collisions: April 26-July 17, 2018] Antimatter-matter annihilation in Tsukuba, Japan

IP size: 400 µm in X, 4 µm in Y Peak Luminosity : 7-9·1031 cm- 2s-1 + - * Probably e e ®g ® qq The scene at the experimental control room in Tsukuba Hall B3

This is scientific history in the making: SuperKEKB/Belle II joins DORIS/ARGUS, CESR/CLEO, and PEP-II/BaBar and KEKB/Belle Welcome to the world of large crossing angle nano-beams !

KEKB SuperKEKB

As expected, the effective bunch length is reduced from ~10 mm (KEKB) to 0.5 mm (SuperKEKB)

We measure this in two track events in Belle II data. How do we measure the vertical height of nanobeams ? Ans: Width of Luminosity scans with diamond detectors B2NOTE-PH-2018-007

1. For early Phase 3, we will continue * with βy =3mm

2. The record is 400 nm and beam currents of only ~15mA

Heading downwards but still struggling with beam- S. Di Carlo et al. (LAL Orsay) beam blow-up (a major issue for Phase 3 too.) Keep on squeezing the two beams with the superconducting * final focus βy =3mm, making sure that the two “thin pancakes” are well aligned. One then adds beam current….. PEP-II design Phase 2, 33 2 33 L = 5.5´10 / cm / sec luminosity 3 x 10 peak July 2018 N.B. Still a long way to go with the superconducting final focus (one order of magnitude * in βy )

Luminosity tuning has priority. When accelerator physicists become tired, Belle II does commissioning or takes data (usually owl shift only). Only able to record ~0.5 fb-1 during Phase 2 pilot run. Belle II Detector (“A Universal Spectrometer”) BEAST (Background commissioning detector) KLong and muon detector: Resistive Plate Chambers (barrel outer layers) Scintillator + WLSF + SiPM’s (end-caps , inner 2 barrel layers)

EM Calorimeter: CsI(Tl), waveform sampling (barrel+ endcap)

Particle Identification electrons (7 GeV) TOP detector system (barrel) Prox. focusing Aerogel RICH (fwd)

Beryllium beam pipe 2cm diameter

Vertex Detector 2 layers DEPFET + 4 layers DSSD positrons (4 GeV) Central Drift Chamber He(50%):C2H6(50%), small cells, long lever arm, fast electronics (Core element) Barrel Particle Identification (uses Cherenkov radiation) The paths of Cherenkov photons from a 2 GeV pion and kaon interacting in a TOP quartz bar. (Japan, US, Slovenia, Italy) Incoming track

Vertexing/Inner Tracking Beampipe r= 10 mm DEPFET pixels (Germany, Czech Republic…) Layer 1 r=14 mm Layer 2 r= 22 mm DSSD (double sided silicon detectors) Layer 3 r=38 mm (Australia) Layer 4 r=80 mm (India) FWD/BWD Layer 5 r=115 mm (Austria) Italy Layer 6 r=140 mm (Japan) +Poland, Korea Advanced & Innovative Technologies used in Belle II Pixelated photo-sensors play a central role MCP-PMTs in the iTOP Collaboration HAPDs in the ARICH with SiPMs in the KLM Industry DEPFET pixel sensors Waveform sampling with precise timing is “saving our butts”. Front-end custom ASICs (Application Specific Integrated Circuits) for all subsystems  DAQ with high performance network switches, large HLT software trigger farm  a 21st century HEP experiment.

KLM (TARGETX ASIC) ECL (New waveform sampling backend with good timing) TOP (IRSX ASIC) New methods of ARICH (KEK custom ASIC) neutron detection with TPC’s for CDC (KEK custom ASIC) the background. SVD (APV2.5 readout chip adapted from CMS) Directions ! The B-anti B meson pairs at the Upsilon(4S) are produced in a coherent, entangled quantum mechanical state. | Y >=| B0 (t , f )B0 (t , f ) > - | B0 (t , f )B0 (t , f ) > 1 1 2 2 2 2 1 1 Need to measure decay times to observe CP violation (particle- antiparticle asymmetry). (PGU: Why is there a minus sign above ?)

One B decays collapses the flavor wavefunction of the other anti-B. (Exercise: Show one B must decay before the other can mix)

Not to scale

The beam energies are asymmetric (7 on 4 GeV) The decay distance is increased by around a factor ~7 Most of the Belle II detector subsystems are working well. Some nice examples of signals involving photons. + - + - e e ® m m g

0 p ® gg

h ® gg Single Photon Lines

Ready for the dark sector ! e+e- ® g X + - e e ® g ALP ® g (gg ) Most of the Belle II detector subsystems are working well. Here are some signals involving charged tracks.

+ - + - K ® p +p - J /y ® m m , J /y ® e e S

No vertex cuts *+ 0 + The signal peaks are charm + - D ® D p , in continuum not B’s e e ® cc 0 - + - + 0 - + - + D ® K p , K p p ,K p p p

Clearly illustrates the capabilities of Belle II and the potential for charm physics and the building blocks of B mesons. TOP Particle Identification D*+ ® D0p + ;D0 ® K -p + s N.B. The charge correlation with the slow pion determines which track is the kaon (or pion)

Kinematically identified kaon from a D*+ in the TOP; Cherenkov x vs t pattern (mapping of the Cherenkov radiation ring) No kaons identified

f ® K - K + inclusive One kaon identified in the TOP.

Another example of TOP particle Both kaons identified in identification the TOP. with early calibration and alignment. Example of unique capabilities in the Phase 2 pilot run

CP Eigenstate: D0 ® K p 0 S

Need a pair of pions with a displaced vertex and two photons measured with good resolution and low background

Comment from LHCb colleagues: “This would be impossible at LHCb.” More matter-antimatter annihilation in Tsukuba: Another event from Belle II’s first evening

+ - * e e ®g ® BB

A potential e+ e- B anti-B candidate Event Topology tells us we are seeing B’s

B pairs produced at rest in the CM with no extra particles

Spherical R2 Jet-like

We are on the 4S We have rediscovered the B meson ! DE = E / 2 - E M = (E / 2)2 - p2 cm recon bc cm recon

History 1983: Now use the full Phase 2 pilot run dataset and apply the FEI (Full Event Interpretation) technique based on boosted decision trees (BDTs, a machine learning technique)

We now observe ~571 fully reconstructed B mesons (389+182) or an improvement of a factor of ~O(3.6) in overall efficiency by using this advanced analysis method that covers many more decay channels. Further improvement (X 2) is definitely possible (PID, low p B2NOTE-2018-031-1, tracking will play a major W. Sutcliffe, F. Bernlochner role). Impact parameter resolution in the Phase 2 pilot run with the BEAST2 VXD Onwards to Phase 3 and the Physics Run SVD +x half-shell, Jan 2018 KEK The VXD has now been installed. Restart Belle II data taking in mid-March 2019.

SVD -x half-shell, July 2018, KEK

PXD layer 1 ladders, Feb 2018

First PXD half-shell being tested at DESY, July 2018 “Full sized” pixel detector module 0

75 μm thick

51 Installation of VXD into Belle II (Nov 21, 2018) Early Phase 3 Physics (March-June, 2019) Plan We assume a plausible scenario with three months in which we integrate luminosity: (2 fb-1, 4 fb-1, 4 fb-1) + 1 fb-1 continuum or ~11 fb-1 for Lepton-Photon 2019 in Toronto, Canada. All detector subsystems, DAQ and trigger will be operating well. Software, calibrations and computing will be ready.

Semileptonic - B→ π l ν and ρ l ν untagged (CLEO saw a signal with 2.66 fb-1)

Time Dependent CP Violation/Charm - D lifetimes (2 fb-1 ) - Doubly Cabibbo suppressed D0 → K+ π-, D0 → K+ π- π0 (10 fb-1) - B lifetimes (2-10 fb-1) - Time dependent B-anti B mixing (10 fb-1) Demonstrate VXD Radiative/Electroweak Penguins physics performance - B→K* γ (b→s) (2 fb-1) rediscover penguins - B→Xs γ (b→s) (~10 fb-1 depending on off-resonance data taking)

Hadronic B decays (not time dependent) ++ Dark Sector Physics - B→K π (b→u) (10 fb-1) Publications - B→ Φ K (b→s) (10 fb-1) - B→J/ψ K (with more significance 2-10 fb-1) P. Urquijo et al. Particle Boys Manga 素粒子男子漫画

• Belle II will explore New Physics on the Luminosity or Intensity Frontier. This is different and complementary to the LHC high pT experiments, which operate on the Energy Frontier. Time for a paradigm shift ?

• There is competition and complementarity with LHCb (@CERN)

• We are ready to start a long physics run in the Super Factory mode (Phase 3) in March 2019. This requires high-efficiency data-taking by Belle II and extensive running by Super KEK-B, soon to be the world’s highest luminosity accelerator.

• The world is waiting for our results. (First ones expected at LP2019) • There are excellent opportunities for collaborators from Vietnam “Breaking news”

First PXD was flown to Japan (business class). This PXD half-shell being installed at KEK, last week. Particle Boys Manga 素粒子男子漫画

• There is competition and complementarity with LHCb (@CERN)

• The world is waiting for our results. (First ones expected at LP2019) Backup Slides

https://en.wikipedia.org/wiki/Kamen_Rider

“Now then, shall we start the experiment ?”

“さぁ、実験を始めようか。 Sa, jikken o hajimeyou ka.”

Sento Kiryu (桐生戦兎 Kiryū Sento), theoretical scientist and character in the “Kamen Rider Build” TV show

東都先端物質学研究所 Touto Sendan Busshitsukakui Kenkyūsho (an imaginary research institute in the TV show) Thanks to Hiro Nakayama Physics Competition and Complementarity

Outside perspective: Belle II inserted into the CERN global schedule. [slide from a plenary talk by Niels Tuning, ICHEP 2018 in Seoul, Korea] Examples of Physics Competition and Complementarity

Use publicly available LHCb projections. Results from Global Fits to Data (CKMFitter Group)

Great progress on ϕ3 or γ (first from B Similar results from UTFIT factories and now in the last four as well from G. Eigen et al. years from LHCb).These measure J. Charles et al, Phys. Rev. the phase of Vub D89 (2014) 033016

NP Phase

Extrapolation to 50 ab-1

NP/SM amplitude ratio

But a 10-20% NP amplitude in Bd Looks good mixing is perfectly compatible (except for an issue with |V |) with all current data. ub 62 How can we establish NP in BK* l-l+ ?

Ans: Observe and measure the rate for Answer B ® snn from and thus isolate the Z penguin (C9) at Belle II Buras et al.

B2SS exercise: Draw the Feynman diagram for this process. Draw this for two cases: kaon and K* in the final state. What’s Ahead ?

“Missing Energy Decay” in a Belle II GEANT4 MC simulation Signal: BK ν ν tag mode: BDπ; DKπ Zoomed view of the vertex View in r-z region in r--phi

64 NP in bs l+l-

Prepared by D. Straub et al. for the Belle II Physics Book (edited by P. Urquijo and E. Kou)

Belle II can do both inclusive and exclusive. Equally strong capabilities for electrons and muons.

65 New Physics Wilson Coefficient for muons What’s ahead: τ Lepton Flavor Violation

Example of the decay topology

Note vertical log-scale (50 ab-1 assumed for Belle II; 3 fb-1 result for LHCb Belle II will push many limits below 10-9 ; LHCb, CMS and ATLAS have very limited capabilities. LHC high pt: The modes τμγ and τ μ h+ h- provide important constraints on Hμτ 66 PGU exercise: Why is the 4S broad while the other three are narrow ?

Event Topology (fits to R2) tells us we are seeing B’s Technical note: R2 = H2/H0 Not so obvious: When we change accelerator optics, we remain on the Upsilon(4S) resonance.

More examples of Physics Competition and Complementarity

Use publicly available LHCb projections. “We need more data !!”

Signal of ~312 events

’ P5

Belle I data. S. Wehle et al. (Belle collab) arXiv: 1612.05014, published in PRL Slide from R. SystematicsMandal from charmonium resonances in ArXiv:1603.04355

Conclusions about the presence of NP 71 unchanged. Results from Global Fits to Data (CKMFitter Group)

PGU Question: What are the x and y axes ?

PGU Question: What is εK ? Why is the band so broad ?

PGU Question: What is Δmd , Δms ? What is their ratio in terms of CKM parameters ?

PGU Question: Why is the

region for Vub a circular disk ?

PGU Question: Where are the measurements of BJ/ψ K ? Why are there two associated regions ?

72 High Energy Physics Spot Check

• What do the acronyms LER and HER stand for ? • Why aren’t the electron and positron beam energies equal ? • Why is a larger current stored in the positron beam ? • BTW, the LHC uses p p collisions rather than proton-anti proton collisions as at the Fermilab Tevatron and earlier hadron colliders. Why ? PGU: What is the GIM (Glashow Illiopoulus-Maiani) Mechanism ? Or GIM suppression ? What is an FCNC (Flavor Changing Neutral Current) ? Hint: “Tsukuba, we have a Problem” (apologies to Tom Hanks, Apollo 13)

WMAP KM Theoretical data prediction

The CP Violation predicted by Kobayashi and Maskawa is too small by ~10 orders of magnitude in the Standard Model.

What does this “Tsukuba: we need some mean ? New Physics”

Belle II has a modern DAQ and readout system

Item to note: Front-end Item to note: Note readout electronics and Gb More on G. Varner’s ROI(Region of fiber optic link(Belle2link) to B2SS talk. Interest) for PXD data the back-end. volume. Performance of CDC dE/dx particle identification with early calibrations in the hadronic event sample.

Jake Bennett, Roy Briere et al. Endcap particle identification via Aerogel RICH (ARICH) ArXiv: 1703.01766, published in Nature 546, 227–233 (08 June 2017) Outer Detector Highlights Belle II Jargon/Acronym Check KLM = [KLong- Muon] detector (Endcap and Barrel) [RPC = Resistive Plate Chamber]; EKLM = Endcap KLM; BKLM= Barrel KLM CsI(Tl) crystals (measures energies of photons et al.) (ECL = Electromagnetic CaLorimeter)

Barrel PID Distinguishes kaons from pions/Cherenkov radiation (iTOP = imaging Time Of Propagation)

Endcap PID Distinguishes kaons from pions/Cherenkov radiation (ARICH = Aerogel Ring Imaging Cherenkov)

CDC = Central Drift Chamber (provides momenta). Via tracking in a 1.5 T B field. History/Background: The Flagship Measurement for the “old” B Factories At the Upsilon(4S), we Boost factors and produce pairs of asymmetric QM entangled B energies: anti-B pairs in a C=-1 state. PEPII/BaBar βγ- 0.56; (9 x 3.1 GeV)

KEKB/Belle βγ-0.43; (8.0 x 3.5 GeV)

SuperKEKB/Belle II βγ=0.284 (7.0 x 4.0 GeV); smaller boost but improved LER lifetime Exercises: and backgrounds; better 1) Why do time-integrated asymmetries acceptance for “missing vanish at the 4S ? energy” decays 2) Verify the βγ factors 83